Sleep mode

Sleep mode saves battery power by putting
HTC One into a low power state while the display is off.
It also stops accidental button presses when
HTC One is in your bag.

Switching to Sleep mode

To turn off the display and switch to Sleep mode, you can:

Briefly press the POWER button.

Double-tap the lock screen.

HTC One also automatically goes into Sleep mode when it’s left idle for a while. You can change the time before
HTC One sleeps by setting the screen timeout. For details, see
Setting when to turn off the screen.